Threats / Zyxel / CVE-2023-33010
CVE-2023-33010
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Zyxel Multiple Firewalls vulnerability
Zyxel firewalls contain an unauthenticated buffer overflow in ID processing enabling denial-of-service and remote code execution.
Verdict
Today item — known-exploited.
A buffer overflow vulnerability in multiple Zyxel firewall models allows unauthenticated attackers to trigger denial-of-service conditions or achieve remote code execution. The vulnerability has been exploited in the wild.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
5 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-05).
Probability (EPSS)
EPSS 0.28813 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Zyxel, Multiple Firewalls. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-120 Buffer Copy without Size Check — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious packet with an oversized ID field to trigger the buffer overflow.
Business
Firewall availability is compromised, disrupting network perimeter defense.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute arbitrary code on the compromised firewall to establish persistence or pivot deeper into the network.
Business
Attackers gain control of critical security infrastructure, enabling lateral movement and data exfiltration.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05